OMJ

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have you tested at all the chilling time of convoluted copper vs straight copper?

Vesku

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Not with same diameter (15mm) tube. I was able to find note's of ½" CFC with 19mm PVC. This was about 2 times longer than the convoluted. My notes say:
"Cooling efficiency when using cooling water at 12C, with approx. 7.5L/min flow:
- water in 82.5C
- water out 20.9C
- gravity fed free flow 3.5L/min"

Carlscan26

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Vesku, I'm having trouble reading this graph...at what time did it drop a couple of degrees and then the faster drop? I don't really see those unless the temp drop,is when the line goes up? Sorry if I'm being dense here...

fafrd

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Vesku,

the video seems to be no longer available. I may be interested to give this a try and would appreciate a chance to see the video if possible. The tool description is suggestive but I do not yet have a clear idea how to make one. Any kind of a quick sketch to help clarify would be greatly appreciated.

Also, can you commend on the wall thickness of the copper tubing you convoluted?

And lastly, do you think there is any hope of this technique working on 0.02" thin-wall stainless tubing?

thanks,

-fafrd

TerraNova

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I am also hoping to do something like this but cant seem to make my jig work based on the written description. Any ideas on how to make this work?

Anyone?

fafrd

Recipes 

Seconding this request. Also interested to know if those who have done this think it would work on thin-wall (0.02") stainless tubing...

-fafrd

cwi

Recipes 

Convoluted tubing is only needed if you aren't flowing fast enough to create turbulent flow . If you aren't creating turbulent flow, it's because your tubing is larger than needed for the flow rate (Reynolds number, or some crap like that). Going down a size can sometimes give superior performance to a larger round tube, and longer smaller tubing will accomplish the same thing as shorter larger convoluted tubing. When just looking at price, more of the smaller tubing is usually a cheaper solution, even if you convolute the tubing yourself.

TerraNova

Recipes 

So just to be clear, you are saying that using a smaller, longer inner tube can create enough turbulence? Or are you saying to size down the outer tubing of the CFC to create turbulence of the coolant?

Sorry to be so thick headed I just want to understand the concept you are describing so I can build the best possible apparatus.

Thanks in advance.

cwi

Recipes 

Nothing wrong with asking, as this is fairly counter-intuitive, like many things.

A benefit of convolutions is to provide turbulence/mixing vs. laminar flow (it also provides minor benefit of a bit higher surface area/cross section ratio- circular tube is perfectly minimized in this regard). The turbulence of both the inner and outer liquid is important. The outer liquid, in this case, is not (usually) constrained to some maximum flow, so getting turbulence there is not (usually) an issue. The inner liquid may be flow constrained by the desired output temp (for single pass cooling). If this flow is insufficient to create turbulence, a smaller diameter tube that provides turbulence at that flow can perform better than the larger non-turbulent flow tube. It may even work at the same length, but the length may also need to be increased to meet the desired temp. That's the theory anyway. There are too many scenarios to describe when larger non-turb beats smaller turb, or vice-versa. I am just giving the rationale behind convoluted tubing, and the alternatives.

The amount of flow to get turbulence isn't that high, especially for circular spirals. I don't have any guidance to provide regarding optimal tubing size, but there have been threads on in it. Or, if you are good at math, there are the Reynolds equations to make some theoretical calcs.

The whole CFC/PC fascination is kind of lost on me, though, especially when recircing to the kettle and/or prechilling is required. I always saw them as only well suited to cases where tap water was cold enough to provide single pass cooling to ferm temps, and you either had a conical, or didn't care about all the cold break getting in your fermenter. Personally, I am an IC believer. Ease of use and simplicity trumps optimized performance in my world.

TerraNova

Recipes 

Thanks for the info. I am gathering all the data I can before building mine. I was thinking of going with a smaller inner tube anyway as EVERYBODY I have spoken to seems to throttle back on the wort going through theirs which a) reduces turbulence and b) reduces surface contact with the inner tubbing.

I agree with not quite getting the benefit of recirculating if a single pass would make you reach pitching temp. It means more things touching your wort as it is cooled which risks infection. It also means you still have to transfer your chilled wort into your fermenting vessel after it is cooled instead of transferring it while cooling it. And since I do a secondary fermentation, I would leave all the cold break behind with the yeast/trub at that point. While cold break in the fermentation tank doesn't hurt the beer, some say it actually helps fermentation (I can't back that claim up though).

The CFC advantage to me is that I switch batch sizes often. I have tried using a smaller IC that was designed for 5 gallon batches on a 10 gallon batch which barely worked (took forever). And when I tried a bigger IC designed for 10 gallon batches about 35-40% of the coils sat above the top of wort in a 5 gallon batch...which didn't hurt the cooling but since I couldn't submerge all of it during the boil it opened it up to infection as an unboiled item was in my wort. Yes, you can sanitize it before placing it in the wort (or try spooning boiling wort over the exposed coils, I guess), which is an extra step (your are sanitizing you transfer lines with an IC anyway, just like you would sanitize a CFC)

A CFC seems to be the right solution for doing any batch size and seems easiest to protect against infections.

As far as pre-chillers go, if your tap water is warm you really have to use it one with either style of apparatus to get down to the temps you may want.